Stable detergent compositions



United States Patent 3,356,612 STABLE DETERGENT COMPOSITIONS David B. Guthrie, St. Louis, Mo., assignor to Petrolite Corporation, Wilmington, Del., a corporation of Delaware No Drawing. Filed Feb. 1, 1965, Ser. No. 429,620 1 Claim. (Cl. 252-99) ABSTRACT OF THE DISCLOSURE Machine dishwashing stable detergent compositions including inorganic alkali metal detergent salts selected from the group consisting of alkali metal carbonates, alkali metal borates, alkali metal polyphosphates, alkali metal hydroxides, and alkali metal silicates, in combination (1) with any suitable halogen-releasing compound such as chlorinated cyanuric acids and salts thereof, Chloramine-T type compounds, the Halozone type compounds, and heterocyclic chlorine-releasing compounds, (2) defoaming nonionic surfactants such as polyalkenoxy type nonionic surfactants such as oxyalkylated compounds of the general formula Z[(OA),,Ol-l} wherein Z is the oxyalkylatable material, A is the radical derived from the alkylene oxide, which can be, for example, ethylene, propylene, butylene oxide, etc., and the like, n is a number determined by the moles of alkylene oxide reacted, for example to 2000 or more and z is a whole number determined by the number of reactive oxyalkylatable groups, and (3) a small but effective amount of antioxidant elfective to reduce, inhibit and/ or prevent the degradation of both the nonionic surfactant and halogen-releasing compounds, thereby rendering both the nonionic surfactant and halogen-releasing compound stable.

This invention relates to detergents containing halogenreleasing compounds including detergent compositions for use in machine dishwashing.

Machine dishwashing is used in connection with practically all commercial and institutional dining facilities as well as in a rapidly increasing proportion of private homes. In commercial machines, the dishes to be washed are introdiic'edinto a zone where detergent solution is sprayed over them, the detergent solution being recycled and used repeatedly and fortified and replenished inter mittently. In home machines the detergent is used for only one load of dishes and is then discarded although it too is recirculated during the washing operation. Hence in both types of machines, food soil concentrations in the wash solution of 0.05 to 0.1% or higher are considered to be moderate under average conditions.

It has been the practice in formulating machine dishwashing detergents to use in the main various combinations of inorganic sodium and potassium salts, such as olyphosphates, silicates, carbonates and basic materials such as sodium and potassium hydroxides. It has not been possible to use effective amounts of well-known organic detergents such as the alkyl aryl sulfonates, alkyl sulfonates, alkanol amides or alkyl aryl polyethers in spraytype mechanical dishwashing detergents because of the foam these materials develop during the washing operation. This foam causes overflow and loss of the wash solution, impairs the mechanical operation of the machine, and lowers the pressure at which the washing fluid is impelled against the utensils to be cleaned. The inorganic materials do not foam themselves and, at low concentrations of food soil (less than 0.01%), perform satisfactorily in mechanical dishwashers. However, with increase in food soil concentration to greater than about 0.03%,

' foaming becomes a serious problem even with the use of purely inorganic detergent systems. This is because the in- Examiz:

3,356,612 Patented Dec. 5, 1967 organic detergent systems, being alkaline, can cause some saponification of fatty food soils. This, plus the natural foaming properties of protein food soils, tends to produce foam in the wash tank.

Recently, certain low foaming, organi detergents have been made available commercially w 1c can be incorporated in small amounts with inorganic materials in mechanical dishwashing formulations without seriously increasing their foaming tendency. These materials add somewhat to the detergency etliciency of the compound formulation. In addition, compounds of this type have been found to have a pronounced effect of inhibiting foam where heavy food soil loads are present, or in maintaining internal wash pressure at a high level under these conditions.

Wash pressure is defined herein as the pressure registered on a manometer or pressure gauge by a Pitot tube set at the outlet of the wash nozzle. The force of the wash spray against a dish surface is directly proportional to this wash pressure. Since it has been shown that the wash action of the wash spray contributes most to gross soil removal, maintenance of the original wash pressure built into the machine is very important.

Excessive foaming in machine dishwashing has-long been a recognized problem and, although billowing foam is an obvious indication of trouble, a real wash pressure problem may exist even without this obvious symptom. For example, an aerated wash solution," though not so easily detected, may be as serious a problem from the standpoint of washing etliciency as billowing foam. An aerated wash solution, as used herein, is defined as a liquid with many small air occlusions or bubbles dispersed in it as contrasted with foam which, as used herein, is defined as a colloidal dispersion of air in liquid floating on top of the wash solution.

Conventional machine dishwashing detergent systems originally were dry, inorganic systems and consisted entirely of mixtures of alkaline salts. The detergent system is required to perform three essential functions: (1) soften the water so that the detersive action can take place more effectively; (2) remove the soil from the dishes thoroughly, completely and rapidly; and (3) leave the dish surface in a state where the water drains in a continuous film without breaking into little hanging drops or streams. Many of the alkaline salts act as both water softeners and soil removers but will be discussed on the basis of their primary function.

Sodium carbonate, although it is among the least effective water-softening agents, together with its sesquicarbonate, is almost universally used as a component in dishwashing compounds, because of its low cost. The detergent i this invention can contain from 0-99% compositions of by weight sodium or potassium rbonate.

The best and most etllcient wa er-softening ingredients I corrosive effect can be overcome by including a relatively large proportion of a silicate in the composition. In this connection, metasilicate is important, not only from the standpoint of the machine itself, but also from the standpoint of the utensils washed. For instance, regardless of whether polyphosphate is present in a solution or not,

3 highly alkaline dishwashing detergents containing no silicates can attack, etch, and darken aluminum utensils. Some of these formulations also have a destructive action on the over-the-glaze dish patterns. Suitable proportions of silicates in the formulation help overcome these difliculties.

The soil-removing ingredients commonly employed in dishwashing compounds include borates and carbonates, which are relatively ineffective, and orthophosphates and metasilicates, both of which are highly effective. The detergent compositions of this invention can include -70% by weight of trisodium or tripotassium phosphate and 0 50% by weight of sodium or potassium metasilicate.

ore recently small amounts of synthetic organic surfactants or wetting agents have been incorporated into machine dishwashing formulations to promote smooth drainage drying, i.e., to prevent water break. Some formulations include from 1% to or more of a low foaming, polyethenoxy type nonionic surfactant. The detergent compositions of this invention can include 0-50% by weight of such synthetic, organic, low foaming polyethenoxy type nonionic surfactants.

onventional machine dishwashing compositions employed for glass and bottle washing normally contain caustic soda as the major cleaning ingredient. Alkalies tend to attack glass surfaces but this can be inhibited by zincates, beryllates, or aluminates. As stated above, sodium gluconate and ethylenediaminetetracetic acid can be used as sequestering agents for high caustic content solutions. The detergent compositions of this invention can include 099% sodium or potassium hydroxide.

Hence the conventional detergent systems into which the polyoxyalkylene glycol mixture is incorporated contain as the principal detersive agent widely varying proportions of sodium or potassum polyphosphates, i.e., 0- .70%, sodium or potassium silicates, i.e., 050%, sodium or potassium carbonates, i.e., 199%, sodium or potassium hydroxides, i.e., 0-100% and trisodium or tripotassium phosphate, i.e., 0-70%. The amount of the polyoxyalkylene glycol mixture ordinarily constitutes about 0.5 to by weight of the final detergent composition.

Since chlorine has long been recognized as an efiicient bleaching and sanitizing agent, its use in elemental form or in the form of chlorine-liberating compounds is widespread. Released chlorine is converted to hypochlorous acid which is recognized to be an effective bleaching and sanitizing agent.

During recent years dry chlorine-releasing compounds have been finding increasing application in new as well as long established consumer and industrial products including machine dishwashing compounds. These dry chlorinereleasing compounds, which are most suitable, have a comparatively high available chlorine content and a relatively long shelf-life.

One family of dry chlorine-releasing compounds which has achieved widespread use comprises the chlorinated cyanurics (such as, for example, trichlorocyanuric acid), salts of the dichlorocyanurates, (such as, for example, sodium dichlorocyanurate, and potassium dichlorocyanurate) and isomers thereof, (such as, for example, trichloroisocyanuric acid and sodium and potassium dichloroisocyanurates), etc.

These cyanurics are being formulated in household and commercial dry bleaches, in some machine dishwashing compositions, in scouring powder, in industrial sanitizers and the like. The key to their broad-scale acceptance has been the following:

(1) High available chlorine content (2) Solid crystalline form suitable for dry blending (3) Rapid solubility in water 4) Stability in dry formulations not containing nonionics (5) No calcium contamination The more successful automatic dishwashing compositions contain chlorine-releasing compounds. The presence of chlorine in a dishwashing compound is desirable for three reasons:

(1) It greatly decreases water spotting of glass and silverware through its improved detergent action (2) It provides mild bleaching and prevents stain buildp (3) It aids in sanitizing dishware Water spotting is reduced owing to the detergent action of chlorine. On a perfectly clean surface, water will sheet" evenly; and any minute quantity of dissolved solids will be deposited so evenly over the entire surface that no unsightly spots develop when the rinse water times. However, when small particles of soil (for example, of the proteinaceous type) remain on the surface, adequate water sheeting is prevented at that area; and after the allotted drain time, droplets of water have formed and remain there. As each droplet dries, it leaves behind an amount of dissolved solids sufficient to cause the formation of unsightly spots. It has been postulated that chlorine is particularly effective in removing protein-type solids because of its ability to oxidize high molecular weight proteins into simple amino acids which are easily removed by the detergent action of the balance of the washing formula. Thus, in essence, in addition to sanitizing, chlorine contributes to the overall cleaning ability of a machine dishwashing formula.

Household dishwashing detergents must combine optimum performance with optimum stability. Best performance is obtained when both an available chlorine compound, such as sodium dichloroisocyanurate, and a defoaming nonionic surfactant are included in the same composition. The available chlorine promotes uniform water sheeting of dishes and glassware by a detergent action that decomposes and dislodges proteinaceous soil whereas the defoaming surfactant suppresses the formation of foam during the cleaning cycle. This combination of available chlorine and a suitable defoaming nonionic surfactant provides spotlessly clean and sanitized dishware including spot-free glasses. Other constituents with machine dishwahing compounds include sodium tripolyphosphate to improve detergency and soften hard water, metasilicate to boost alkalinity and prevent soft metal corrosion, and soda ash to buffer the high alkalinity provided by the metasilicate.

In regard to stability, some loss of chlorine from the sodium dichloroisocyanurate occurs during storage. One cause is attributed to moisture pickup with the net result that there is a reaction of the sodium dichloroisocyanurate with the alkaline builders; this loss is greatly accelerated when a defoaming nonionic surfactant is in the same dishwashing composition. Attempts to control this loss by the following compounding techniques have been unsatisfactory:

(1) Coating the most alkaline components (metasilicate and soda ash) with the liquid nonionic surfactant. This procedure was designed to reduce the tendency of these alkaline materials to react with the sodium dichloroisocyanurate when moisture entered the package as well as minimize the reaction between the nonionic and the sodium dichloroisocyanurate by physically separating them. It is advantageous not to mix the nonionic surfactant directly with the sodium dichloroisocyanurate.

(2) Adding the sodium tripolyphosphate only after all the nonionic surfactant has been taken up by the more alkaline components. This leaves the tripolyphosphate uncoated so that it can absorb entering moisture preferentially and tie it up as a stable hydrate. Hydrolysis of the sodium dichloroisocyanurate during storage is thus limited and chlorine loss minimized.

In actual practice, the above mentioned compounding techniques are not effective in providing suitable shelflife stability when a chlorine-releasing compound and a defoaming nonionic surfactant are employed in the same formulation. The problem of formulating automatic or machine dishwashing compositions having both available nonionic defoaming surfactant is further complicated by the fact that nonionics are degraded by the alkaline constituents as well as the chlorine released by the chlorine-releasing compound during storage.

Stated another way, oxyalkylated compounds of the nonionic type are unstable in the presence of alkaline materials. When nonionics of this type are employed in alkaline machine dishwashing compounds not containing a chlorine-releasing agent, they tend to degrade upon storage. Thus, the dishwashing composition does not have suflicient shelf-life to yield a completely satisfactory product. For example, when certain defoaming nonionic detergents are employed and formulated in alkaline dishwashing compositions, they tend to degrade and result in losing their ability to defoarn; and as a result, the dishwashing composition becomes unsatisfactory because the amount of defoaming surfactant remaining is unable to control the natural foaming tendency which develops when proteinaceous soil is in contact with the alkaline constituents. This increase in foaming is extremely detrimental to the operation of dishwashing machines because it prevents pumps and sprays from operating properly.

I have now discovered that, when nonionics are employed in conjunction with an antioxidant, the degradation of both nonionics and chlorine-releasing compounds can be reduced, inhibited and/or prevented. Stated another way, both the chlorine-releasing compound and the nonionics, when employed together in the same formulation, are rendered much more stable when in contact with an antioxidant. For example, during storage the chlorine loss of the chlorine-releasing compounds and the degradation of the nonionic is greatly minimized by incorporating an antioxidant in the system. Although described primarily in relation to dishwashing compositions, this invention is applicable to all formulations including laundry formulations in which chlorine-releasing compounds are employed with nonionics.

A small but effective amount of antioxidant is employed in this invention, i.e., effective in reducing, inhibiting and/or preventing the degradation of nonionic and/ or chlorine-releasing compounds.

Since a wide variety of chlorine-releasing compounds, nonionics, and antioxidants and other components can be employed in the detergent system, the eflective amount of antioxidant will vary widely. In practice I employ at least about 0.01% by weight such as from about 0.1 to 10.0%, for example from about 0.3 to 5.0%, but preferably from about 0.5 to 2.0% based on weight of either chlorine-releasing compounds or nonionic surfactant in the formulation.

In general, both the chlorine-releasing compounds and the nonionic as employed in the formula are each less than about 5% by weight of the total formulation, but more can be employed if desired. The ratio of chlorinereleasing compound to nonionic can also vary, such as from 5:1 to 1:5, but are in general employed in ratios of 3:1 to 1:3 but preferably in about equal amounts.

W1 e y nonionics can be employed in this invention. In general, the nonionics employed are oxyalkylated compounds of the general formula wherein Z is the oxyalkylatable material, A is the radical derived from the alkylene oxide which can be, for example, ethylene, propylene, butylene oxide, etc., and the like, u is a number determined by the moles of alkylene oxide reacted, for example to 2000 or more and z is a whole number determined by the number of reactive oxyalkylatable groups. Where only one group is oxyalkylatable as in the case of a substituted or unsubstituted monofunctional phenol, a straight chain biodegradable alcohol, or a branched-chain alcohol, then z=1. It is known that normal alchohols are biodegradable-such as, those obtained 'by saponification of natural waxes such as sperm oil, those obtained by reduction of fatty acids derived chlorine and from coconut oil, palm kernel oil, or tallow and those obtained from petroleum sources, such as for example, the mixtures of C through C straight-chain primary alcohols now commercially available from Continental Oil Co. Where Z is water, or a glycol, 2:2. Where Z is glycerol, z=3, etc.

As is well known, alkylene oxides can be reacted with various oxyalkylatable materials (i.e., materials which contain hydrogen atoms capable of reacting with a 1,2 alkylene oxide) to form polyalkylene oxide derivatives thereof. Thus, where an oxyalkylatable material of the formula ZH is reacted with an alkylene oxide such as ethylene oxide, there is obtained a compound of the formula I. Z L(OA)..OH]

such as where n is a number determined by the moles of alkylene oxide reacted and z is a number determined by the compounds oxyalkylatable hydrogens.

Many polyalkylene oxide 'block polymers have been prepared containing definite homogeneous block units or segments of ethylene oxide, propylene oxide, butylene oxide, etc., such as disclosed in U.S.P. 2,674,619, 2,677,- 700 and elsewhere.

Where ethylene oxide is reacted with water, a polymeric polyethylene glycol of the type H(OEt) -O(EtO),,H is formed. Similarly, where propylene oxide is reacted with Water, a polymeric polypropylene glycol of the type H(OPr) O(PrO) H is formed. When water is first reacted with ethylene oxide followed by reaction with propylene oxide, a polymer containing blocks of ethylene oxide units and blocks of propylene oxide are formed, H(OPr),,,(OEt),,O-(Et0),,(PrO) H, or when added in the reverse order the following block polymer is formed:

Block polymers of this type can be formed by adding rinfinite numbers of block units, for example,

This block-wise or sequential addition could be continued infinitely. Since only two types of alkylene oxides are employed, these polymers are di-block polymers.

Where three or more different types of alkylene oxides are employed, ter-block polymers are formed as illustrated by sequentially adding ethylene oxide, propylene oxides, and butylene oxides to water to form:

These ter-block units may also be continued infinitely. Where, for example, other alkylene oxides are used in addition to ethylene, propylene, and butylene oxides, a higher type of block polymer is formed, such as when octylene oxide or styrene oxide are additionally reacted. It is to be noted that block units of these polymers within themselves are homogeneous units, i.e., each block is derived from a single alkylene oxide.

Polyalkylene oxides have also been prepared by reacting mixtures of alkylene oxide such as when a mixture of ethylene oxide and propylene oxide are reacted. When this is done, a random or hetero-polymer is obtained. Thus, for example, where a 50/5 e Eedwin ox e-"- s I as water, one obtains a'polymer having no orderly arrangement of the alkylene oxide units since the distribution of EtO and PrO units in the molecule is random may be designated by 7 where MO represents a random distribution of B and PrO units such as, for example,

M0 as employed herein refers to mixtures of ethylene oxide in conjunction with a hydrophobic alkylene oxide, i.e., an alkylene oxide having more than two carbon atoms. Thus, the hydrophobic alkylene oxides include propylene oxide, butylene oxide, amylene oxide, octylene oxide, styrene oxide, methylstyrene oxide, cyclohexene oxide, etc. However, in practice I prefer to employ ethylene oxide in conjunction with propylene and/or butylene oxide.

The alkylene oxides employed herein are 1,2-alkylene oxides of the formula wherein R R R and R are selected from the group consisting of hydrogen, an aliphatic, cycloaliphatie, aryl, etc., group for example ethylene oxide, propylene oxide, butylene oxide, amylene oxide, octylene oxide, styrene oxide, methylstyrene oxide, cyclohexene oxide (where R, and R are joined to make a ring), etc.

Equivalents of alkylene oxides can also be employed, for example alkylene carbonates, i.e., ethylene carbonate, propylene carbonate, butylene carbonate, etc. In addition, alkylene oxides of the glycide, methyl glycide type can also be employed.

Since the products of this invention are preferably block polymers containing blocks or segments of alkylene oxide units which are added sequentially, the reaction is in essence a stepwise procedure. For the sake of simplicity of presentation, the invention will be illustrated by employing as a base oxyalkylatable compound ZH and by employing only ethylene, propylene, and butylene oxides with the understanding that other hydrophobe oxides can be used in place of propylene and butylene oxides such as amylene oxide, octylene oxide, styrene oxide, etc. These are shown in the following table.

The products formed are represented by means of a statistical formula and are often referred to as eogenerie mixtures. This is for the reason that if one selects any oxyalkylatable material and subjects it to oxyalkylation, particularly where the amount of oxide added is comparatively large, for example units of EtO, it is well known that one does not obtain a single constituent such as RO(C H.,O) H. Instead one obtains a cogenerie mixture of closely related homologous compounds in which the formula may be shown as the following:

where X as far as the statistical average goes, is 30, but the individual members present in significant amounts may vary from compounds where x has a value of 25 and perhaps less to a point where x may represent or more (see Flory Chemical Reviews, vol. 30, No. l, page 137). Thus, the formulae presented herein are statistical formulae.

TABLE I Step II.Reaction of the Step I product with one of the five oxides or mixtures employed in Step I, which oxide had not been reacted in the immediately preceding step. For example: [(EtO)n( )m ]z )n( )m ]z Step IV involves the oxyalkylation of the products of Step 111. Step V involves the oxyalkylation of Step IV. Further oxyalkylations involve Steps IV-X or higher. This process can be continued ad infinitum.

Where Z is derived from ZH which is H O, z=2. Where Z is derived from ZOH, Z is the moiety of an alcohol or a phenol and 2 Where Z is derived from a polyol such as glycerol, z 2. Examples of 201-1 include the following:

( 1 Oxyalkylatable rnonofunctiqnal cpmpoundsJuch as alc'ohcfl's"6f'thE"C;H GH-series for examplemethi aiiol,'e'thario:l, fpropahohbutanol, pentanol, hexanol, octanoi nonanol, decanol,.nndecanol, dodecanol, triedecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, etc. (2) Corresponding unsaturated alcohols, for example oleyl, linoleyl alcohols, (3) phenolic compounds including those of the general formula (a) Polyhydric alcohols Ethylene glycol Propylene glycol Diethylene glycol Trimethylene glycol 2,3-butanediol 1,4-dihydroxy-2-butene 1,12-dihydroxy octadecane 1,4-dihydroxy cyclohexane 10 2,2-dimethyl-l,3-propanediol 2ethyl-2-butyl propanediol-l,3 Glycerol Erythritol Sorbitol Mannitol Inositol Trimethylol propane Pentaerythritol Polyallyl alcohol Bis (4-hydroxycyclohexyl) dimethyl methane 1,4-dimethylol benzene 4,4'-dimethylol diphenyl Dimethylol xylenes Dimethylol naphthalenes, etc. (b) Polyhydric ether alcohols Diglycerol Triglycerol Dipentaerythritol Tripentaerythritol Dimethylolanisoles Beta hydroxyethyl ethers of polyhydric alcohols and phenols such as Diethylene glycol Polyethylene glycols Bis(beta hydroxyethyl ether) of hydroquinone Bis(beta hydroxyethyl ether) of bisphenol Beta hydroxyethyl ethers of glycerol, pentaerythritol,

sorbitol, mannitol, etc. condensates of alkylene oxides such as ethylene oxide; propylene oxide; butylene oxide; isobutylene oxide; glycidol; glycid ethers, etc., with polyhydric alcohols such as the foregoing. (c) Polyhydric phenols Hydroquinone Resorcinol Pyrogallol Bisphenol (predominantly 4,4-dihyd1'oxy diphenyl dimethyl methane) Dihydroxy diaryl sulfones (d) Phenol-aldehyde resins See US. Patent 2,499,365

The molecular weight of the nonionics of this invention can vary widely from such as 500 to 100,000, or higher, for example a range of 1,000 to 25,000, preferably 1,500- 7,000 with an optimum of 2,0005,000. However, the specific preferred and optimum molecular weight will vary with each particular application.

The moles of alkylene oxide on each block unit can also vary widely, such as from 5-200 moles, or more, of alkylene oxide, for example, a range of 10-150 moles with an optimum of 15-60 moles per block unit. However, the range of the specific preferred block unit will vary with the specific surfactant molecule and with the system in which the surfactant is employed.

In general the nonionics which are most effective in the practice of this invention are those which contain more than one kind of alkylene oxide, either in random distribution, in block formation or both. Where the nonionic is a block polymer, it is preferred that the terminal group be derived from a hydrophobe alkylene oxide, i.e., one other than EtO, preferably PrO. If the terminal block is derived from ethylene oxide, then the block 50 derived preferably should contain less alkylene oxide molar units than the immediately preceding hydrophobe alkylene oxide block.

Preferably, the nonionics should be a low foaming surfactant. In uses where biodegradability is important, it is preferable that the nonionic be biodegradable.

One class of defoaming nonionics useful in this invention comprises a polyoxayalkylene glycol mixture consisting of a product which statistically represented has a plurality of alternating hydrophobic and hydrophilic polyoxyalkylene chains or segments, the hydrophilic chains (segments) consisting of oxyethylene radicals linked one to the other and the hydrophobic chains (segments) consisting of oxypropylene radicals linked one to the other, said statistically represented product having five such chains (segments) comprising three hydrophobic chains (segments) linked by two hydrophic chains, the central hydrophobic chain (segment) constituting 30% to 34% by weight of the final product, the terminal hydrophobic chains (segments) together constituting 31% to 39% by weight of the final product, the linking hydrophilic chains (segments) constituting 31% to 35% by weight of the final product, the intrinsic viscosity of the final product being from about 0.06 to 0.09 and the molecular weight of the final product being from about 3,000 to 5,000.

The polyoxyalkylene glycol mixture is prepared by condensing propylene oxide with water or propylene glycol to form a polyoxypropylene glycol, condensing ethylene oxide with the resulting polyoxypropylene glycol, and then condensing propylene oxide with the resulting oxyethylated polyoxypropylene glycol. The preparation must be carried out in the above order to yield products having the required alternating hydrophobe-hydrophile structure.

These are described in U.S. Patents 3,048,548 and 3,082,172 which are by reference incorporated into this application.

The compositions of this invention can also be employed as rinse agents for use in machine dishwashing as described in U.S. Patent 3,082,172.

Another class of defoaming nonionic surfactant useful in this invention comprises a polyoxyalkylene glycol mixture consisting of a product which, statistically represented, has three or more alternating hydrophobic and hydrophilic segments. In this class of surfactant the first segment is hydrophobic such as that derived from a dior multi-substituted phenol, for example, a didodecyl phenol. The first hydrophilic segment of polyoxyethylene units is attached thereto and may be as low as 80 weight percent of the starting hydrophobe. Then the second hydrophobic segment (such as that derived from polyoxypropylene units) is attached thereto and may be as low as 115 weight percent of the starting hydrophobe. In such an example, the step of alternating first with a polyoxyethylene segment and then a polyoxypropylene segment may be carried out eight times. On the other hand, where only one hydrophilic segment of polyoxyethylene units is attached to the starting hydrophobe, the ethylene oxide employed may be as high as 460-625 weight percent of the starting hydrophobe and the final hydrophobic segment of polyoxypropylene units attached thereto may be as high as 675-900 weight percent of the starting hydrophobe.

Still another class of deforming nonionic surfactant useful in this invention comprises a polyoxyalkylene glycol mixture consisting of a product which, statistically represented, has three or more alternating hydrophobic and hydrophilic segments such that the first hydrophobic segment is derived from a biodegradable straight-chain primary alcohol, for example, nC I-l OH. Then, the first hydrophilic segment of polyoxyethylene units is attached thereto and may be as low as 94 weight percent of the starting hydrophobe. Then the second hydrophobic segment (such as that derived from polyoxypropylene units) is attached thereto and may be as low as 200 weight percent of the starting hydrophobe. In such an example, the step of alternating first with a polyoxyethylene segment and then a polyoxypropylene segment may be carried out at least six times. One the other hand, when only one hydrophilic segment of polyoxyethylene units is attached to the starting hydrophobe, the ethylene oxide employed may be as high as 565-850 weight percent of the starting hydrophobe and the final hydrophobic segment of polyoxypropylene units attached thereto may be as high as 1240-1850 weight percent of the starting hydrophobe.

A wide variety of anti-oxidants including both primary or donor type anti-oxidants and synergists can be employed which are capable of inhibiting, preventing or reducing degradation of the chlorine-releasing compound and the nonionic surfactant. The mechanism by which this inhibition of degradation occurs in no way limits the scope of this invention. Heretofore published mechanisms of antioxidant activity may or may not take place under the conditions of this invention because the customary concept about antioxidation is complicated by the presence of a chlorine-releasing compound. Antioxidants of the primary and synergist types are widely described in the literature and are of the types employed in foods, foodstufis, soaps and cosmetics, pharmaceuticals, essential oils, fats, petroleum, rubber and textile oils, etc. Antioxidants of these types are described in Autooxidation & Antioxidants, vols. I and II by Lundberg (Interscience Publishers, 1962), which are by reference incorporated into the present application. The antioxidants permitted in foods by the Food & Drug Administration are suitable for use in this invention. These include, for example, the following primary antioxidants: gum guaiac; tocopherols and related compounds; NDGA (nordihydroguaiaretic acid); gallic acid and the gallates (such as propyl gallate); BHA (butylated hydroxyanisole); Bl-lT (butylated hydroxytoluene). Also included, for example, are the synergists: phospholipids, such as lecithin; citric acid; phosphoric acid; monoisopropyl citrate; stearyl citrate; ascorbic acid and related compounds such as sodium ascorbate, isoascorbic acid, sodium isoascorbate and ascorbyl palmitate', and thiodipropionic acid and related compounds such as didodecyl and dioctadecyl thiodipropionate, etc.

In addition, the primary antioxidants employed in stabilizing petroleum and rubber compositions are usitable in the invention and include: the mono-, diand trialkylphenols, alkylated bisphenols, alkylated dihydroxyaomatic compounds and amino-phenols such as, for example,

2,6 li-tbutyl phenol,

2,6-di-t-butyl-4-methyl phenol, bis(4-hydroxy-3,5-di-t-butyl)methane, 4'dimethylaminomethyl-2,6-di-t-butyl phenol, p-n-butylaminophenol, 4,4'-dihydroxy-3,3'-dimethyl-5,5-di-t-butyl biphenyl, 2,2'-methylene-bis(4-methyl-6-t-butyl phenol), butylated-4-rnethoxyphenol, butylated-4-hydroxy-toluene,

2,5-di-t-butyl hydroquinone,

2,5-di-amyl hydroquinone,

catechol, and

resorcinol;

Amino compounds, such as diarylamines and t-alkyl primary amines examples of which are:

mixed alkylated diphenylamines, a-naphthylamine,

phenyl a-maththylamine, phenyl-fl-naphthylamine, di-sec-butyl p-phenylene diamine, N-phenyl-N'-cyclohexyl-p-phenylene diamine, N,N-diphenyl-p-phenylene diamine, phenothiazine, 9,9-dimethylacridone,

t-dodecyl primary amine, and t-octadecyl primary amine;

and miscellaneous antioxidants such as:

6,6'-bis(4-methyl-2-t-butylphenyl) sulfide, zinc dithiocarbonates,

zinc benzothiazolethione, and

guanidine derivatives.

13 The following table presents examples of commercial antioxidants which are advantageously employed in this invention:

TABLE II Antioxidants Commercial or Trade Name 1. I001) om: armoxmsms 1. Dilauryithiodipropionate Dillydap. 2. Distearyl thiodipropionate Dlsterdap. 3. B,B-Thiodipropionlc acid. 4. Butylated hydroxy-anisole Tenox BHA. 6. Butylated hydroxy-inlnn'no Tenox BHT, Dalpac 200, Food Grade BH'I. 6. n-Propyl gallate 'Ienox PG. 7. Mixtures of 4, 5, and 6 Grimth G-50 u. must. man came 1,2dihydro-6-ethoxy-2,2,4-trlrnethy1quinoline Santoquln.

m. nu. arrnovnn 2,2'-rnethylene his-(kmethyl-o-t-butylphenol) CAO 5, CA 14.

IV. nunnrsn AND cssouxn canon 1. 2,2-methylene bis-(4-methyl-6-t-butylphenol)..- Antioxidant 2246. 2. Dicyclohexylamine 8. Mixtures of 1 and 2 4, Phenothlmino 5. Phenothiazine-CuCl.-- 6. Polybutyiated bisphenol A Agerite Supcrlite. 7. 4,4-methylene bis-(d-t-butylo-cresol) Antioxidant 720. 8. 4,4'-methylene bis-(2,6-di-t-butylphenol) Antioxidant 702.

VJQBCELLANEOUB o-Tolyl higflanlde Sopanox. Oxyalkylated t-butylphenolformaldehyde condensation pr 'Iretolite ltd-75.

Any suitable halogen-releasing compound such as a chlorine-releasing compound can be employed. Those most important from a commercial point of view are of the cyanurate type and include chlorinated cyanuric acids and salts thereof, including but not limited to the following commercial examples: trichlorocyanuric acid, sodium dichloroisocyanurate, potassium dichloroisocyanurate, and isomers thereof.

In addition to noionics, chlorine-releasing compounds beside the cyanurates can be employed, such as by way of example, those of the chloramine-T type, such as sodium N-chloro-p-toluene-sulfonamide, the chloramine- B type, such as sodium N-chlorobenzenesulfonamide, the Halozone type such as (N,N-dichloro-p-carboxybenzenesulfonamide) and the like, heterocyclic chlorine-releasing compounds, such as those of the trichloromelarnine type, those of the dichlorodimethylhydantoin type, etc.

In addition to nonionics, chlorine-releasing componds and antioxidants, other constituents employed in detergent compositions can be employed such as those described herein. These include carbonates, phosphates, silicates and other components of dishwashing compositions.

The following examples are presented for purposes of illustration and not of limitation.

A typical diswashing compound with active chlorine was employed in all the examples. It had the following formula:

Percent Sodium carbonate 41 Sodium tripolyphosphate 30 Sodium metasilicate, anhydrous 25 Potassium dichloroisocyanurate 2 Defoaming nonionic surfactant 2 The dishwashing compounds for storage testing were prepared in the following manner:

A 2000 g. quantity of each test blend was made according to the proportions shown in the above formulation. A technique, recommended by the many formulators,

G. Sodium tripolyphosphate 600 Sodium metasilicate (anhydrous) 500 Sodium carbonate 660 These ingredients were mixed well for about one minute and then 200 g. of the preblended surfactant on Na CO was added thereto.

These ingredients were mixed well by rolling for 15 minutes. Then 40 g. potassium dichloroisocyanurate was added.

This final mixture was blended for 20 minutes on a roller and then proportioned into two one-pint jars with screw-cap lids for storage in each of two ovens, maintained at 122-128 F. and l00-l00 F., respectively.

The jars were removed from the respective storage temperatures from time to time, mixed well; and samples of the contents were tested for ability to retard the formation of foam according to the procedure for the FOAM RETARD TEST. Samples of the contents, also, were evaluated for active chlorine content by the method for ACTIVE CHLORINE DETERMINATION.

FOAM RETARD TEST (1) Basis for test:

The typical amount of cleaning compound (containing about 2% defoaming nonionic surfactant) usually charged to a dishwashing machine is about Mi /s ounce/gallon of water. In brief, this is calculated as 7.1-9.4 g./gallon for the dishwashing compound and 0.142 to 0.188 g./ gallon (or 38-50 p.p.m.) for the defoaming nonionic surfactant (assuming that none has been lost by decomposition) in the wash water. Examples: For a Kitchen Aid dishwasher with a capacity of about 2% gallons per wash, this is equivalent to using 16.5 to 22 g. of the dishwashing compound; and for the foam machine at about 1.2

gallons per wash, this is equivalent to using 8.5 to 11.3

g. of dishwashing compound.

The amount of food soil selected for this test (i.e., 5 cc. whole egg) is sufficient to cause a very rapid formation of foam, when exposed to the action of a dishwashing compound not containing defoaming nonionic surfactant. For example, a five-inch height of foam will develop within 30-60 seconds over a water surface area of sq. inches.

As was previously explained, foaming must be sup pressed in order to have adequate cleaning ability. In this test a drop in water pressure is observed when the foam height reaches two inches. Accordingly, we have arbitrarily set one inch of foam as the maximum amount of foam which can be tolerated while maintaining eifective cleaning ability.

The FQAM RETARD TEST is run for ten minutes; this period of time is two minutes longer than the eightminute wash cycle for a Kitchen Aid dishwasher.

(2) Procedure:

Rinse foam machine well-twice with cold water and twice with the hot water as it is supplied from a hot water tank.

Drain well.

A heel of 650 ml. B 0 is left in the pump and piping of the system.

Charge dishwashing compound, in quantities of 5 g., 7.5 g., 10 g., 12.5 g., 15 g., 17.5 g. or 20 g. At the start of each stability test, these amounts of dishwashing compound contain undegraded defoaming nonionic surfactant in amounts sufiicient to supply the washwater with con- 15 centrations of 22, 33, 44, 55, 66, 77 or 88 p.p.m. respectively.

Charge 3850 ml. hot water (temperature should be about 175 F.) (The total water charge is about 4500 ml). Turn pump on and recycle water until homogeneous. (Temperature of washwater should drop below 160 F. and should be held above 140 F.)

Foam height should be less than $4 inch. Charge ml. of whole egg from a syringe and continue circulation through foam machine. Start stop watch as soon as egg is charged. Record foam height after 30 seconds and 1, 3, 5, 6, 7, 8, 9 and minutes.

(3) Evaluation:

Readings below one inch after eight minutes is considered good retard action and is considered a passing performance. More than one-inch of foam after eight minutes is a failing retard action. (Readings of less than )4 inch after eight minutes is excellent retard action.)

ACTIVE CHLORINE CONTENT DETERMINATION Run in duplicate:

(1) Weight to four places 12.5 g. dishwash formulation containing active chlorine compound. (Potassium dichloroisocyanurate, KCl (NCH),, mol. wt. 236, theoretical chlorine content 30.1%; theoretical active chlorine content, also, is 30.1%.) Use glassine paper at about 0.3 g. Weigh compound to about 12.8 g. gross weight. Charge to 500 ml. Erlenmeyer flask or a 500 ml. iodine flask containing magnetic stirrer. Weigh glassine paper for exact weight.

(2) Disolve sample in 230 ml. distilled water.

(3) Add 10 ml. benzene +5 cc. CHCI (To extract oxyalkylate sulfactant and iodine and to reduce foaming during addition of acid.)

(4) Stir vigorously with magnetic stirrer to extract oxyalkylate.

(5) While mixing thoroughly, add ml. sulfuric acid (diluted 1:1 by volume with water). Avoid too rapid an evolution of C0 (6) Add 7.5 g. KI dissolved in 20 ml. distilled water (or 22-23 ml. of solution made by dissolving 453.6 g. KI in 1210 ml. distilled water). Mix vigorously momentarily.

(7) Add standarized Na S O solution slowly with mixing, until colorless. (Starch-iodine indicator is not required.)

(8) Record mls. of standardized Na S 0 Calculation:

% Active Chlorine in formulation= Ml. Na S O X Normality Na spsx 1.773 Sample Weight of Formulation Active Chlorine Remaining= Active chlorine of sample Active chlorine of formulation without Surfactant at zero time The results of the FOAM RETARD TEST are presented in Tables HI and IV. The term Days of Adequate 60 (B) Reaction product of one mole didodecylphenol 70 011:: I

with moles ethylene oxide and moles propylene oxide.

(C) Reaction product of one mole water with about 45 moles propylene oxide, about moles ethylene oxide and finally with about 60 moles propylene oxide.

The antioxidants employed are as follows:

(I) Santoquin (1,2-dihydro 6 ethoxy-2,2,4-trimethyl quinoline).

(II) Phenothiazine.

(III) t-butylphenol-formaldehyde resin.

(IV) antioxidant 2246 [2,2'-methylene bis-(4-methyl- 6-t-butylphenol) (V) dicyclohexylamine.

TABLE TIL-FOAM RETARD TEST-DISHWASHING FORMULATION WITH ACTIVE CHLORINE [Storage results at 125 F.)

Days of Adequate Detoaming Surfactant Antioxidant 10 g. 12.5 g. 15 g. or less or less 1 or less 1 The arrows indicate slightly more or less than the figure given TABLE IV.FOAM RETARD TEST-DISHWASHING FOR- MULATION WITH ACTIVE CHLORINE [Storage results at 100-100 F.)

Days of Adequate Defoaming Surfactant Antioxidant 7.5 g. or 10 g. or 12.5 g. or 15 g. or

less less less I less I III 6 11 None 2 II ll 18 24 III 7 18 IVIV 7 18 None 1 II 6 ll 22 20 III B 11 22 29 IV/V 8 11 22 29 None 3 8 1 12.5 g. is equivalent to about Me more than astandard dishwash charge I 15 g. is ulvalent to about )6 more than a standard dishwash charge: '40 parts and 60 parts V were used throughout all the tests.

TABLE V.-ACTIVE CHLORINE CONTENT DETERMINA 'IION-DISHWABHING FORMULATION WITH ACTIVE CHLORINE (AC) [Storage results at 125 F.]

ac- Anti- Days to De 5 to Da 5 to De s to tant oxidant 90% AC BWZAC 7 0 AC 0 AC fi ure time of the last analysis.

TABLE VI.ACTIVE CHLORINE CONTENT DETERMINA- TIONDISHWASHING FORMULATION WITH ACTIVE CHLO RINE (AC) [Storage Results at 100-110 F.]

As is quite evident, antioxidants, chlorine-releasing compounds and nonionics will be constantly developed which could be useful in this invention. It is, therefore, not only impossible to attempt a comprehensive catalogue of such compositions, but to attempt to describe the invention in its broader aspects in terms of specific chemical names of its components used would be too voluminous and unnecessary since one skilled in the art could by following the description of the invention herein select a useful composition. This invention lies in the use of suitable antioxidants in conjunction with suitable chlorine-releasing compounds and nonionics and their individual compositions are important only in the sense that their properties can affect this function. To precisely define each specific useful antioxidant, chlorine-releasing compound and nonionic in light of the present disclosure would merely call for chemical knowledge within the skill of the art in a manner analogous to a mechanical engineer who prescribes in the construction of a machine the proper materials and the proper dimensions thereof. From the description in this specification and with the knowledge of a chemist, one will know or deduce with confidence the applicability of specific antioxidants, nonionics, and chlorine-releasing compounds suitable for this invention by applying them in the compositions set forth herein. In analogy to the case of a machine, wherein the use of certain materials of construction or dimensions of parts would lead to no practical useful result, various materials will be rejected as inapplicable where others would be operative. One can obviously assume that no one will wish to employ a useless system nor will be misled because it is possible to misapply the teachings of the present disclosure to do so. Thus, any antioxidant, nonionic and chlorine- 18 releasing compound system that can perform the function stated herein can be employed.

Having thus described my invention what I claim as new and desire to obtain by Letters Patent is:

A stable detergent composition for machine dishwashing consisting essentially of a mixture of sodium carbonate, sodium tripolyphosphate and anhydrous sodium metasilicate, a defoaming type surfactant selected from the group consisting of (A) the reaction product of one mole n-C H OH with 30 moles ethylene oxide and 50 moles propylene oxide,

(B) the reaction product of one mole didodeeylphenol with 45 moles ethylene oxide and 50 moles propylene oxide and (C) the reaction product of one mole water with about 45 moles propylene oxide, about moles ethylene ogtide and finally with about 60 moles propylene oxe,

potassium dichloroisocyanurate, and an antioxidant selected from the group consisting of (A) 1,2-dihydro-6-ethoxy-2,2,4-u-imethy1 quinoline,

(B) phenothiazine,

(C) t-butylphenol-formaldehyde resin,

(D) d[2,2-methylene bis (4-methyl-6-t-butylphenol)] (E) dicyclohexylamine, said antioxidant being present in an amount sufficient to reduce, inhibit and prevent degradation of both said nonionic surfactant and said potassium dichloroisocyanurate, whereby both said nonionic surfactant and said potassium dichloroisocyanurate are rendered stable thereby providing a stable detergent composition.

References Cited UNITED STATES PATENTS 3,054,753 9/1962 Hurt et al 252- X 3,108,078 10/1963 Wixon 252-95 3,110,677 11/1963 Karabinos et al. 252-99 3,112,274 11/ 1963 Morgenthaler et al. 252-95 X 3,248,330 4/1966 Feierstein et a1. 252-99 3,250,720 5/1966 Moore 252-187 3,255,117 6/1966 Knapp et a1. 252-99 3,278,443 10/1966 Bright et a1. 252-95 3,281,370 10/ 1966 Coward et al. 252-99 FOREIGN PATENTS 849,907 9/ 1960 Great Britain.

LEON D. ROSDOL, Primary Examiner.

M. WEINBLATI, Assistant Examiner. 

